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Fix GH-13681: segfault when adding watchpoint fails. #14513

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Fix GH-13681: segfault when adding watchpoint fails. #14513

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dfa53ae
Fix GH-13681: segfault when adding watchpoint fails.
devnexen Jun 8, 2024
80da0a8
add test
devnexen Jun 8, 2024
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15 changes: 9 additions & 6 deletions sapi/phpdbg/phpdbg_watch.c
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Original file line number Diff line number Diff line change
Expand Up @@ -316,7 +316,7 @@ void *phpdbg_watchpoint_userfaultfd_thread(void *phpdbg_globals) {

struct uffd_msg fault_msg = {0};
while (read(globals->watch_userfaultfd, &fault_msg, sizeof(fault_msg)) == sizeof(fault_msg)) {
void *page = phpdbg_get_page_boundary((char *)(uintptr_t) fault_msg.arg.pagefault.address);
void *page = phpdbg_get_page_boundary((char *)(uintptr_t) fault_msg.arg.pagefault.address);
zend_hash_index_add_empty_element(globals->watchlist_mem, (zend_ulong) page);
struct uffdio_writeprotect unprotect = {
.mode = 0,
Expand Down Expand Up @@ -665,7 +665,7 @@ void phpdbg_watch_parent_ht(phpdbg_watch_element *element) {
}

void phpdbg_unwatch_parent_ht(phpdbg_watch_element *element) {
if (element->watch->type == WATCH_ON_BUCKET) {
if (element->watch && element->watch->type == WATCH_ON_BUCKET) {
phpdbg_btree_result *res = phpdbg_btree_find(&PHPDBG_G(watch_HashTables), (zend_ulong) element->parent_container);
ZEND_ASSERT(element->parent_container);
if (res) {
Expand Down Expand Up @@ -966,11 +966,14 @@ void phpdbg_remove_watchpoint(phpdbg_watchpoint_t *watch) {
}

void phpdbg_clean_watch_element(phpdbg_watch_element *element) {
HashTable *elements = &element->watch->elements;
phpdbg_unwatch_parent_ht(element);
zend_hash_del(elements, element->str);
if (zend_hash_num_elements(elements) == 0) {
phpdbg_remove_watchpoint(element->watch);

if (element->watch) {
HashTable *elements = &element->watch->elements;
zend_hash_del(elements, element->str);
if (zend_hash_num_elements(elements) == 0) {
phpdbg_remove_watchpoint(element->watch);
}
}
}

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39 changes: 39 additions & 0 deletions sapi/phpdbg/tests/gh13681.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
--TEST--
phpdbg_watch null pointer access
--CREDITS--
Yuancheng Jiang
--SKIPIF--
<?php
if (getenv('SKIP_ASAN')) {
die("skip intentionally causes segfaults");
}
?>
--FILE--
<?php
echo "*** Testing array_multisort() : Testing with anonymous arguments ***\n";
var_dump(array_multisort(array(1,3,2,4)));
$xconnect=$GLOBALS[array_rand($GLOBALS)];
echo "Done\n";
$a = [];
$a[0] = 1;
$a[0] = 2;
$a = [0 => 3, 1 => 4];
?>
--PHPDBG--
b 6
r
w a $a
c
q
--EXPECTF--
[Successful compilation of %s]
prompt> [Breakpoint #0 added at %s:%d]
prompt> *** Testing array_multisort() : Testing with anonymous arguments ***
bool(true)
Done
[Breakpoint #0 at %s:%d, hits: 1]
>00006: $a = [];
00007: $a[0] = 1;
00008: $a[0] = 2;
prompt> prompt> [Script ended normally]
prompt>
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